Minimum Liquid Flowrate Formula:
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Definition: This calculator determines the minimum liquid flowrate required in an absorption column to achieve a specified gas purification.
Purpose: It helps chemical engineers design absorption columns for gas purification processes by calculating the minimum solvent requirement.
The calculator uses the formula:
Where:
Explanation: The formula calculates the minimum solvent flow needed to achieve the desired gas purification based on equilibrium relationships.
Details: Proper calculation ensures efficient column operation, optimal solvent usage, and meets purification requirements without excessive costs.
Tips: Enter the gas flowrate, inlet and outlet gas mole fractions, equilibrium constant, and inlet liquid mole fraction. All values must be valid (denominator cannot be zero).
Q1: What happens if the denominator becomes zero?
A: The calculation becomes invalid. This occurs when \( \frac{Y_{N+1}}{\alpha} = X_0 \), meaning the inlet liquid is already in equilibrium with the inlet gas.
Q2: What's a typical equilibrium constant value?
A: This varies widely (0.1-10+) depending on the gas-solvent system and temperature. For CO2 in water at 20°C, it's about 1.4-1.6.
Q3: Why use solute-free mole fractions?
A: Solute-free basis simplifies calculations as the carrier gas and solvent flows remain constant throughout the column.
Q4: How does this relate to actual operating flowrates?
A: Actual flowrates are typically 1.2-2.0 times the minimum to ensure efficient mass transfer.
Q5: What if my outlet gas mole fraction is higher than inlet?
A: This would indicate a stripping operation rather than absorption, requiring a different calculation.